A294757
Expansion of Product_{k>=1} 1/(1 - k^k*x^k)^(k^k).
Original entry on oeis.org
1, 1, 17, 746, 66442, 9843731, 2187951485, 680615166718, 282199710311343, 150389915850565698, 100155578811552469018, 81505577529171038120173, 79580089696277797740768316, 91814299717377746850767747558
Offset: 0
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N=20; x='x+O('x^N); Vec(1/prod(k=1, N, (1-k^k*x^k)^k^k))
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sd(n) = sumdiv(n, d, d^(d+n+1));
a(n) = if (n==0, 1, sum(k=1, n, sd(k)*a(n-k))/n); \\ Michel Marcus, Nov 10 2017
A294699
Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of Product_{j>=1} (1-j^(k*j)*x^j)^j(k*j) in powers of x.
Original entry on oeis.org
1, 1, -1, 1, -1, -1, 1, -1, -16, 0, 1, -1, -256, -713, 0, 1, -1, -4096, -531185, -64711, 1, 1, -1, -65536, -387416393, -4294405135, -9688521, 0, 1, -1, -1048576, -282429470945, -281474581032631, -95363000655153, -2165724176, 1, 1
Offset: 0
Square array begins:
1, 1, 1, 1, ...
-1, -1, -1, -1, ...
-1, -16, -256, -4096, ...
0, -713, -531185, -387416393, ...
0, -64711, -4294405135, -281474581032631, ...
A294773
a(n) = Sum_{d|n} d^(d+n+1).
Original entry on oeis.org
1, 33, 2188, 262273, 48828126, 13060753578, 4747561509944, 2251799880796161, 1350851717674586413, 1000000000152587898818, 895430243255237372246532, 953962166441299506564257602, 1192533292512492016559195008118
Offset: 1
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a[n_] := DivisorSum[n, #^(# + n + 1) &]; Array[a, 13] (* Amiram Eldar, Oct 04 2023 *)
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{a(n) = sumdiv(n, d, d^(d+n+1))}
Showing 1-3 of 3 results.
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